Around the world, the sand fly has acquired a variety of strange names - granny nipper, punkie, no-see-um. These tiny insects, about one quarter the size of a typical mosquito, are nocturnal, silently feeding from dusk to dawn. It is why in Italy they are called Pappataci, a combination of the words for silent and feed.
But while their bite can often go unnoticed, its impact can be deadly - both to people and animals.
Female phlebotomine sand flies are the principal carriers of leishmaniasis, a parasitic disease found in more than 90 countries around the world and one that can devastate lives.
When Leishmania parasites enter the body of their host they are recognized and attacked by the host's immune cells but they survive and multiply within them, developing mechanisms to evade or control the immune response. While most people and animals infected by the parasites will not actually develop the disease, those with weaker immune systems can be vulnerable to developing a range of symptoms from skin lesions to potentially fatal organ failure.
For humans, leishmaniasis comes in three forms – visceral, cutaneous and mucocutaneous. Visceral leishmaniasis, also known as kala-azar, is the most serious form of the disease, with up to 90,000 new cases worldwide each year, leading to as many as 30,000 deaths, predominantly in the poorest parts of the world.
It is the same story for animals, where the disease, depending on the immune response, can cause skin lesions, swollen lymph nodes, weight loss and lethargy, and if left untreated ultimately even death.
A disease that disproportionately affects dogs
One of the main reservoirs for Leishmania parasites are dogs, as well as other wild canids like foxes and wolves. Canine leishmaniasis occurs on almost all continents, but it is particularly a problem in Latin America and Southern Europe, where an estimated 2.5 million dogs are infected with the parasite.
It is also spreading. A combination of climate change and the greater movement of affected dogs and people has seen an increase in cases of leishmaniasis in previously disease-free areas. As the average temperature has increased, sand flies are surviving in more northern regions and can feed off infected carriers.
In Italy, for example, the disease has been endemic in the south for some time but it has now spread north. It means that for vets and pet owners across the country, the threat of leishmaniasis is a very real one.
So what can be done to protect our pets and reduce the risk of infection in both dogs and people in these regions?
The importance of prevention
“For every disease we know that prevention is better than treatment. But particularly for leishmaniasis this is true,” says Professor Gaetano Oliva, Veterinary Clinical Sciences, Faculty of Veterinary Medicine, University of Naples. “The best suggestion that we can give to owners is that every dog must be treated with products that have a repellent effect to prevent them from being bitten. Not only the healthy dogs but also the infected or sick ones because they are the source of the parasite for sand flies.”
Repellent products typically come in formats that are applied topically to the animal, such as spot-on pipettes or collars. They contain active ingredients which spread over the body surface via the lipid layer of the skin. As a result, these products act on sand flies as soon as they come into contact with the animal so there is no need to bite. Some collars have the additional benefit of providing longer lasting protection.
And these preventative measures are not only important in blocking the bites of infected sand flies but also the bites of ticks and fleas, which are not only a nuisance but can transmit other dangerous diseases, such as canine babesiosis and ehrlichiosis.
It is therefore critical that pet owners are aware of the need to continuously protect their pets through prevention, such as with repellent products. The good news is this is increasingly the case.
“The awareness among owners regarding protection and repelling external parasites, such as ticks, fleas and mosquitoes, has increased in recent years, while the treatments available have diversified greatly,” Dr Claudio Amore, medical director of the Amore veterinary clinic, Province of Salerno, Italy.